Recently, in tires used in heavy duty and high speed conditions such as aircraft tires, the radial structure is employed for the purposes of structural durability, running performance and fuel consumption. In such aircraft tires, however, since they are used in the conditions of high internal pressure, heavy load and high speed, a greater durability is required as compared with tires used in other fields. Especially the bead part is likely to be peeled or damaged in the carcass end part, and its vicinity, due to the strain caused by bending deformation by a large load at the time of taking off or landing. Therefore, it was hitherto attempted to suppress bending deformation by enhancing the bead rigidity, by increasing the bead volume, or using a reinforcement layer made of organic or inorganic fiber cords.
In such rigidity reinforcing measures, however, the internal heat generation due to bending deformation cannot be decreased, and satisfactory prevention of bead part damage could not be obtained.